1. Field of the Invention
The invention relates to the use of silicone resins as dispersants for solids.
For the dispersing of solids (e.g., fillers or pigments) in liquid media it is regular practice to make use of dispersants in order to achieve effective dispersing of the solids, to reduce the mechanical shear forces required for dispersing, and at the same time to realize very high degrees of filling. The dispersants assist the disruption of agglomerates, as surface-active materials wet and/or cover the surface of the particles to be dispersed, and stabilize said particles against unwanted reagglomeration.
In the production of inks and paints dispersants facilitate the incorporation of solids, such as fillers and pigments, for example, which, as important formulating ingredients, are essential determinants of the optical appearance and of the physicochemical properties of inks and paints. Optimum utilization requires firstly that these solids be distributed uniformly in the formulations and secondly that the state of distribution, once attained is stabilized.
2. Description of the Related Art
A host of different substances are nowadays used as dispersants for solids. In addition to very simple, low molecular mass compounds, such as lecithin, fatty acids and their salts, and alkylphenolethoxylates, for example, more complex structures, too, are used as dispersants. The use particularly of amino-functional and amido-functional systems is widespread here. WO-A-00/24503 describes, for example, dispersants based on polyester-modified polyamines. DE-A-1 97 32 251 describes salification products of polyamines and their use as dispersants for pigments and fillers. Furthermore, for example, WO-A-99/56864, EP-B-0 154 678, EP-A-0 159 678 and EP-A-0 438 836 describe dispersants based on polyurethanes. Additionally amino-functional and/or amido-functional poly-acrylates (EP-B-0 879 860) are used.
There is nevertheless a growing demand for solids dispersants which exhibit properties further improved over those of the prior art. The demand is for dispersants which have a very high stabilizing effect on a multiplicity of different solids. For example with more effective dispersants it is possible to reduce the amount of high-price pigments used without having to accept detractions in terms of color strength.
Moreover, for example the viscosity characteristics of inks and paints comprising solids, such as fillers and/or pigments, are critically codetermined by the dispersant used. The demand here is in particular for dispersants which result in a very low viscosity in the liquid inks and paints and also retain such a viscosity, preference being given to newtonian viscosity behavior.